JP5085383B2 - Substrate glass blank for information recording medium, substrate for information recording medium, and manufacturing method of information recording medium - Google Patents

Substrate glass blank for information recording medium, substrate for information recording medium, and manufacturing method of information recording medium Download PDF

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JP5085383B2
JP5085383B2 JP2008070698A JP2008070698A JP5085383B2 JP 5085383 B2 JP5085383 B2 JP 5085383B2 JP 2008070698 A JP2008070698 A JP 2008070698A JP 2008070698 A JP2008070698 A JP 2008070698A JP 5085383 B2 JP5085383 B2 JP 5085383B2
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glass
information recording
recording medium
press
molding
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JP2009221089A (en
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伸広 前田
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Hoya Corp
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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B11/00—Pressing molten glass or performed glass reheated to equivalent low viscosity without blowing
    • C03B11/06—Construction of plunger or mould
    • C03B11/08—Construction of plunger or mould for making solid articles, e.g. lenses
    • C03B11/088—Flat discs

Description

本発明は、情報記録媒体用基板ガラスブランク、情報記録媒体用基板、情報記録媒体およびそれらの製造方法に関する。   The present invention relates to an information recording medium substrate glass blank, an information recording medium substrate, an information recording medium, and methods for producing the same.

ハードディスクなどの情報記録媒体用基板の材料として、ガラスや結晶化ガラスが用いられている。こうしたガラス基板を生産する方法の一つとして熔融ガラスをプレス成形型に供給し、ガラスが冷却、固化する前に薄板円盤状にプレス成形し、得られたガラスブランクに外周面加工、中心孔開け加工、表裏一対の主表面を研削、研磨する加工を施して中心孔付きのガラスディスクを作る方法が知られている。この方法の一例は、特許文献１に開示されており、熔融ガラスから基板の形状に近似したガラスブランクを直接成形するため、非常に生産性に優れている。   Glass and crystallized glass are used as materials for substrates for information recording media such as hard disks. One method for producing such glass substrates is to supply molten glass to a press mold, press it into a thin disk before the glass cools and solidifies, and then process the outer peripheral surface and open the center hole in the resulting glass blank. There is known a method of making a glass disk with a center hole by processing and grinding and polishing a pair of front and back main surfaces. An example of this method is disclosed in Patent Document 1, and since a glass blank that approximates the shape of a substrate is directly formed from molten glass, the productivity is extremely excellent.

特許文献２に記載の方法は、特許文献１に記載の方法を改良したもので、上下型の中心軸の傾きによる平行度の悪化、ガラスの量の変動によるブランクの肉厚バラつきを抑制しようとするものである。この方法では上下型の間にスペーサーを入れ、ガラスの外周面とスペーサーとを非接触状態に保ちながら、プレス成形する。   The method described in Patent Document 2 is an improvement of the method described in Patent Document 1, and attempts to suppress the deterioration of the parallelism due to the inclination of the central axis of the upper and lower molds, and the variation in the thickness of the blank due to the variation in the amount of glass. To do. In this method, a spacer is inserted between the upper and lower molds, and press molding is performed while keeping the outer peripheral surface of the glass and the spacer in a non-contact state.

特許文献３に記載の方法は、特許文献２に記載の方法で得たブランクの中心孔開け位置を外周面を用いず、重心位置とし、孔開けを行うという方法である。
特開平７−１３３１２１号公報 特開２００３−５４９６５号公報 特開２００３−６３８３１号公報 The method described in Patent Document 3 is a method in which the center hole position of the blank obtained by the method described in Patent Document 2 is set to the center of gravity position without using the outer peripheral surface, and the hole is formed.
JP 7-133121 A JP 2003-54965 A JP 2003-63831 A

特許文献２、３の方法は、外周面を加工フリーとするため、外周面の形状、ブランクの外径が成形ごとに異なり、外周面を中心孔の位置を決めるための基準に使用することができない。こうした問題をブランクの重心位置を求め、その位置に中心孔を開けるという方法で解決しようとしている。   In the methods of Patent Documents 2 and 3, since the outer peripheral surface is processed free, the shape of the outer peripheral surface and the outer diameter of the blank are different for each molding, and the outer peripheral surface can be used as a reference for determining the position of the center hole. Can not. We are trying to solve this problem by finding the center of gravity of the blank and making a central hole at that position.

しかし、この方法は外周面加工を省くことができる一方、大量生産されたブランクの重心を一枚ずつ測定しなければならず、膨大な手間がかかる。   However, this method can save the outer peripheral surface processing, but the center of gravity of the mass-produced blank has to be measured one by one, which takes enormous effort.

本発明は、こうした問題を解決し、平面視したときの真円度に優れるとともに外径公差が小さく、外周面を加工しなくても中心孔開け位置の決定が容易で、主表面間の平行度が優れた情報記録媒体用基板ブランクを量産する方法、前記ブランクから情報記録媒体用基板と情報記録媒体を製造する方法を提供することを目的とする。   The present invention solves these problems, has excellent roundness when viewed in plan, has a small outer diameter tolerance, and can easily determine the center drilling position without processing the outer peripheral surface, and the parallelism between the main surfaces. An object of the present invention is to provide a method for mass-producing a substrate blank for an information recording medium having an excellent degree and a method for producing a substrate for an information recording medium and an information recording medium from the blank.

本発明は以下のとおりである。
［１］
軟化状態のガラス塊を一対の押圧型でプレス成形する工程を繰り返し行ってガラスブランクを量産する、略円盤状の情報記録媒体用基板ガラスブランクの製造方法において、
繰り返し行われる前記プレス成形は、一対の押圧型の成形面の距離が一定の値になるまで所定量のガラス塊をプレスすること、
軟化状態のガラス塊をプレスして一対の押圧型の対向する２つの成形面に沿ってガラスを伸ばし、伸ばしたガラスの全外周に外周規制面を転写して、ガラスブランクの一対の主表面と外周面を成形するとともに、
成形面の外周部または前記外周部の外側にあって対向する成形面の距離より大きい間隔を有する2つの面および外周規制面によって少なくとも区画される、前記押圧型のキャビティ内の外周に設けられた、肉厚部成形用空間の一部に前記伸ばしたガラスを侵入させて、ガラスブランクの外縁の少なくとも一部に肉厚部を成形する(但し、上記ガラスブランクの外縁の肉厚とならない部分は、前記ガラスブランクの一対の主表面の厚みと少なくとも等しい厚みを有する)こと、
プレス成形毎に供給するガラス塊の量の変動に応じて、肉厚部成形用空間へのガラスの充填度を変化させること、但し、プレス成形毎に供給するガラス塊の量の変動幅および肉厚部成形用空間の容量は、ガラスブランクの外縁の少なくとも一部に肉厚部が形成されるが、肉厚部成形用空間の容量を超えてガラスが充填されない範囲で設定される、
ことを特徴とする情報記録媒体用基板ガラスブランクの製造方法。
［２］
肉厚部を全周にわたり成形することを特徴する［１］に記載の情報記録媒体用基板ガラスブランクの製造方法。
［３］
プレスの際の、一対の押圧型の成形面の距離の前記一定の値は、０．７〜３．０ｍｍの範囲に設定する［１］または［２］に記載の情報記録媒体用基板ガラスブランクの製造方法。
［４］
ガラスブランクは、
（１）一方の主表面の外縁を平坦とし、他方の主表面の外縁を凸部として肉厚部とするか、
（２）両方の主表面の外縁を凸部として肉厚部とすることを特徴とする［１］〜［３］のいずれかに記載の情報記録媒体用基板ガラスブランクの製造方法。
［５］
ガラスブランクは、一方または両方の主表面の中央部に凸部を設けたものである［１］〜［４］のいずれかに記載の情報記録媒体用基板ガラスブランクの製造方法。
［６］
押圧型は、型閉めした状態で上型と下型とが直接当接する構造を有する［１］〜［５］のいずれかに記載の情報記録媒体用基板ガラスブランクの製造方法。
［７］
前記押圧型の一方が前記外周規制面を備え、
前記供給されたガラスは、前記肉厚部の凸部を形成する表面の一部または全部が型に接触せずに自由表面となっていることを特徴とする［６］に記載の情報記録媒体用基板ガラスブランクの製造方法。
［８］
軟化状態のガラス塊が熔融ガラス塊であり、この熔融ガラス塊を一方の押圧型の成形面中央に供給してプレス成形する［１］〜［７］のいずれかに記載の情報記録媒体用基板ガラスブランクの製造方法。
［９］
肉厚部成形用空間の容量は、
プレス成形毎に供給するガラス塊の量の変動により生じると想定される最大量のガラスが、肉厚部成形用空間以外の押圧型のキャビティ内に隙間が生じないように均一に供給されたと想定した場合に、肉厚部成形用空間においてガラスが占める断面積の１１０％〜２００％の断面積を持つように設定されることを特徴とする［１］〜［８］のいずれかに記載の情報記録媒体用基板ガラスブランクの製造方法。
［１０］
［１］〜［９］のいずれかに記載の方法でガラスブランクを製造し、製造したガラスブランクの外周面を基準に中心孔開け位置を定め、中心孔開け加工する工程、中心孔開け加工したブランクの２つの主表面を研削する工程、研削した主表面を研磨する工程を有する情報記録媒体用基板の製造方法。
［１１］
プレス成形で成形した平坦な主表面を基準にして、主表面の研削を行う［１０］に記載の情報記録媒体用基板の製造方法。
［１２］
プレス成形で成形した外縁の肉厚部を基準にして、主表面の研削を行う［１０］に記載の情報記録媒体用基板の製造方法。
［１３］
［１０］〜［１２］のいずれかに記載の方法で基板を作製し、作製した基板上に情報記録層を含む膜を形成する工程を有する情報記録媒体の製造方法。 The present invention is as follows.
[1]
In the manufacturing method of a substantially disc-shaped substrate glass blank for an information recording medium in which a glass blank is mass-produced by repeatedly performing a step of press-molding a softened glass lump with a pair of pressing dies,
The press molding performed repeatedly is to press a predetermined amount of glass lump until the distance between the molding surfaces of the pair of pressing dies becomes a constant value,
Press the softened glass lump to stretch the glass along two opposing molding surfaces of the pair of pressing dies, transfer the outer peripheral regulating surface to the entire outer periphery of the stretched glass, While molding the outer peripheral surface,
Provided on the outer periphery in the cavity of the pressing mold, which is at least defined by the outer peripheral part of the molding surface or the outer surface of the outer peripheral part and at least partitioned by two surfaces having a larger distance than the opposing molding surface and the outer peripheral regulating surface , By allowing the stretched glass to penetrate into a part of the thick part forming space, and forming a thick part on at least a part of the outer edge of the glass blank (however, the part that does not become the thickness of the outer edge of the glass blank is , Having a thickness at least equal to the thickness of a pair of main surfaces of the glass blank),
The filling degree of the glass into the thick part forming space is changed according to the fluctuation of the amount of glass lump supplied for each press forming, provided that the fluctuation range and the thickness of the amount of glass lump supplied for each press forming are changed. The capacity of the thick part forming space is set in a range where the thick part is formed on at least a part of the outer edge of the glass blank, but the glass is not filled beyond the capacity of the thick part forming space,
The manufacturing method of the substrate glass blank for information recording media characterized by the above-mentioned.
[2]
The method for producing a substrate glass blank for an information recording medium according to [1], wherein the thick part is formed over the entire circumference.
[3]
The substrate glass blank for an information recording medium according to [1] or [2], wherein the constant value of the distance between the molding surfaces of the pair of pressing dies at the time of pressing is set in a range of 0.7 to 3.0 mm. Manufacturing method.
[4]
Glass blank
(1) The outer edge of one main surface is flattened and the outer edge of the other main surface is a convex part, or a thick part,
(2) The method for producing a substrate glass blank for an information recording medium according to any one of [1] to [3], wherein the outer edges of both main surfaces are convex portions to form a thick portion.
[5]
The glass blank is a method for producing a substrate glass blank for an information recording medium according to any one of [1] to [4], wherein a convex portion is provided at the center of one or both main surfaces.
[6]
The pressing mold is a method for producing a substrate glass blank for an information recording medium according to any one of [1] to [5], wherein the upper mold and the lower mold are in direct contact with each other when the mold is closed.
[7]
One of the pressing molds includes the outer peripheral restriction surface,
In the information recording medium according to [6], in the supplied glass, a part or all of a surface forming the convex portion of the thick portion is a free surface without being in contact with a mold. For manufacturing substrate glass blanks.
[ 8 ]
The softened glass lump is a molten glass lump, and the molten glass lump is supplied to the center of the molding surface of one of the pressing molds and press-molded. The information recording medium substrate according to any one of [1] to [ 7 ] Manufacturing method of glass blank.
[ 9 ]
The capacity of the thick part molding space is
It is assumed that the maximum amount of glass that is assumed to be generated due to fluctuations in the amount of glass lump supplied at each press molding is supplied uniformly so that there is no gap in the cavity of the pressing mold other than the thick part forming space. The thick section forming space is set so as to have a cross-sectional area of 110% to 200% of a cross-sectional area occupied by the glass in the thick part forming space, according to any one of [1] to [ 8 ], A method for producing a substrate glass blank for an information recording medium.
[10]
A glass blank is produced by the method according to any one of [1] to [ 9 ], a center drilling position is determined with reference to the outer peripheral surface of the manufactured glass blank, and a center drilling process is performed. A method for manufacturing a substrate for an information recording medium, comprising a step of grinding two main surfaces of a blank and a step of polishing the ground main surface.
[11]
[ 10 ] The method for manufacturing a substrate for an information recording medium according to [ 10 ], wherein the main surface is ground with reference to a flat main surface formed by press molding.
[12]
[ 10 ] The method for manufacturing a substrate for an information recording medium according to [ 10 ], wherein the main surface is ground on the basis of the thick portion of the outer edge formed by press molding.
[13]
The manufacturing method of the information recording medium which has the process of producing the board | substrate by the method in any one of [ 10 ]-[ 12 ], and forming the film | membrane containing an information recording layer on the produced board | substrate.

本発明によれば、平面視したときの真円度に優れるとともに外径公差が小さく、外周面を加工しなくても中心孔開け位置の決定が容易で、主表面間の平行度が優れた情報記録媒体用基板ブランクを量産することができる方法を提供できる。さらに本発明によれば、本発明の方法により調製されたブランクから情報記録媒体用基板と情報記録媒体を製造する方法も提供することができる。   According to the present invention, the roundness when viewed in plan is excellent, the outer diameter tolerance is small, the center hole position can be easily determined without processing the outer peripheral surface, and the parallelism between the main surfaces is excellent. A method capable of mass-producing a substrate blank for an information recording medium can be provided. Furthermore, according to this invention, the method of manufacturing the board | substrate for information recording media and the information recording medium from the blank prepared by the method of this invention can also be provided.

［ブランクの製造方法］
プレス成形後のブランク加工工程を省力化するには、ブランクを平面視したときの真円度、外径公差、両主表面間の距離（肉厚）の公差、両主表面間の平行度を同時に高精度化する必要がある。外径公差については好ましくは±０．１ｍｍ以内、肉厚公差については好ましくは±０．０１５ｍｍ以内、平行度については好ましくは０．０１ｍｍ以内といった高精度化が求められる。 [Blank manufacturing method]
In order to save labor in the blanking process after press molding, roundness, outer diameter tolerance, distance between both main surfaces (thickness) tolerance, and parallelism between both main surfaces when the blank is viewed in plan view At the same time, it is necessary to increase the accuracy. High accuracy is required such that the outer diameter tolerance is preferably within ± 0.1 mm, the thickness tolerance is preferably within ± 0.015 mm, and the parallelism is preferably within 0.01 mm.

特別な工夫を施していないプレス成形型、成形装置を用いて、こうした要求を同時に満たすブランクを量産するためには、プレス成形型に供給するガラスの質量公差を０．１％以内に抑える必要がある。例えば、一定流出量で流出する熔融ガラス流を一定の時間間隔で分離し、一定重量のガラス塊を上記質量公差で得ようとすると、上記時間間隔を１／１０００秒オーダーで安定化しなければならない。しかし、このような質量公差でガラス塊を得ることは、流出ガラスの熱間切断制御の現状の技術レベルでは達成困難である。現状の技術レベルでは、型に供給するガラスの量の０．２％〜５％程度の変動は避けられない。   In order to mass-produce blanks that satisfy these requirements at the same time using press molds and molding equipment that have not been specially devised, it is necessary to keep the mass tolerance of the glass supplied to the press mold within 0.1%. is there. For example, if a molten glass flow that flows out at a constant flow rate is separated at a constant time interval and a glass lump with a constant weight is to be obtained with the mass tolerance, the time interval must be stabilized on the order of 1/1000 second. . However, obtaining a glass lump with such a mass tolerance is difficult to achieve with the current technical level of hot cutting control of outflow glass. At the current technical level, a fluctuation of about 0.2% to 5% of the amount of glass supplied to the mold is inevitable.

こうしたガラス量の変動の影響を低減するため、特許文献２、３は真円度、外径公差の高精度化を犠牲にし、その上で肉厚公差、平行度の高精度化を図る。   In order to reduce the influence of such fluctuations in the amount of glass, Patent Documents 2 and 3 sacrifice high accuracy of roundness and outer diameter tolerance, and further increase accuracy of thickness tolerance and parallelism.

しかし、本発明者は、真円度、外径公差、肉厚公差、両主表面間の平行度には影響を与えない部位に余剰分のガラスを逃がせば、すべての要求を満足することが可能になるのではないか、という着想に基づき、略円盤状のブランク主表面の外縁に余剰ガラスを逃がす方法を検討した。その結果、本発明を完成させるに至った。   However, the present inventor can satisfy all the requirements by letting excess glass escape to the part that does not affect the roundness, outer diameter tolerance, wall thickness tolerance, and parallelism between the two main surfaces. Based on the idea that this could be possible, a method for allowing excess glass to escape to the outer edge of the substantially disk-shaped blank main surface was studied. As a result, the present invention has been completed.

なお、余剰ガラスの量とは、目的とする外径、肉厚を有する理想的な円盤形状のブランクを得るために必要なガラスの質量をM、実際にプレスするガラスの質量をｍとしたときにｍ−Mで表される量である。   The amount of surplus glass means that the mass of glass necessary to obtain an ideal disk-shaped blank having the desired outer diameter and thickness is M, and the mass of the glass to be actually pressed is m. Is the amount represented by m-M.

本発明は、軟化状態のガラス塊を一対の押圧型でプレス成形する工程を繰り返し行ってガラスブランクを量産する、略円盤状の情報記録媒体用基板ガラスブランクの製造方法である。さらにこの方法において以下の(1)〜(5)を特徴とする。
(1)前記プレス成形は、一対の押圧型の成形面の距離が所定の値になるまで所定量のガラス塊をプレスすること
(2)軟化状態のガラス塊をプレスして一対の押圧型の対向する２つの成形面に沿ってガラスを伸ばし、伸ばしたガラスの全外周に外周規制面を転写して、ガラスブランクの一対の主表面と外周面を成形すること
(3)成形面の外周部または前記外周部の外側にあって対向する成形面の距離より大きい間隔を有する2つの面および外周規制面によって少なくとも区画される、前記押圧型のキャビティ内の外周に設けられた、肉厚部成形用空間の一部に前記伸ばしたガラスを侵入させて、ガラスブランクの外縁の少なくとも一部に肉厚部を成形する(但し、上記ガラスブランクの外縁の肉厚とならない部分は、前記ガラスブランクの一対の主表面の厚みと少なくとも等しい厚みを有する)こと
(4)プレス成形毎に供給するガラス塊の量の変動に応じて、肉厚部成形用空間へのガラスの充填度を変化させること
(5)プレス成形毎に供給するガラス塊の量の変動幅および肉厚部成形用空間の容量は、ガラスブランクの外縁の少なくとも一部に肉厚部が形成されるが、肉厚部成形用空間の容量を超えてガラスが充填されない範囲で設定されること。 The present invention is a method for producing a substantially disc-shaped substrate glass blank for an information recording medium in which a glass blank is mass-produced by repeatedly performing a step of press-molding a softened glass lump with a pair of pressing dies. Further, this method is characterized by the following (1) to (5).
(1) In the press molding, a predetermined amount of glass lump is pressed until the distance between the molding surfaces of the pair of pressing dies reaches a predetermined value.
(2) Press the softened glass lump to stretch the glass along two opposing molding surfaces of a pair of pressing dies, transfer the outer periphery regulating surface to the entire outer circumference of the stretched glass, Molding the main surface and outer peripheral surface
(3) The outer periphery of the pressing die is at least defined by the outer peripheral portion of the pressing die or at least the outer surface of the outer peripheral portion and the two outer surfaces having an interval larger than the distance between the opposing molding surfaces and the outer peripheral regulating surface. The stretched glass is allowed to enter a part of the thick part forming space provided, and the thick part is formed on at least a part of the outer edge of the glass blank (however, the thickness of the outer edge of the glass blank and The portion that must not have a thickness at least equal to the thickness of the pair of main surfaces of the glass blank)
(4) Change the filling degree of the glass into the thick part forming space according to the fluctuation of the amount of glass lump supplied for each press forming.
(5) The fluctuation range of the amount of glass lump supplied for each press forming and the capacity of the thick part forming space are such that a thick part is formed on at least a part of the outer edge of the glass blank. It must be set in a range that does not fill the glass beyond the space capacity.

一般に、情報記録媒体用基板ガラスブランクは、研削、研磨によって情報記録媒体用基板に加工される略円盤状の情報記録媒体用基板ガラスブランクである。本発明は、このガラスブランクスを、軟化状態のガラス塊を一対の押圧型でプレス成形する工程を繰り返し行って量産する方法である。   Generally, the substrate glass blank for information recording media is a substantially disc-shaped substrate glass blank for information recording media that is processed into a substrate for information recording media by grinding and polishing. The present invention is a method for mass-producing this glass blank by repeatedly performing a step of press-molding a softened glass lump with a pair of pressing dies.

(1)成形面の距離が所定の値になるまで所定量のガラス塊をプレス
本発明の製造方法におけるプレス成形では、一対の押圧型を用いる。
この一対の押圧型を用いて、一対の押圧型の成形面の距離が所定の値になるまで所定量のガラス塊をプレスする。プレス成形は、一対の押圧型の成形面の距離が所定の値になるまで行われる。所定の値は、例えば、０．７〜３．０ｍｍの範囲であり、成形面の距離の変動許容範囲は、例えば、 ±０．０１５μmの範囲である。 (1) Press a predetermined amount of glass lump until the distance between the forming surfaces reaches a predetermined value . In press forming in the manufacturing method of the present invention, a pair of pressing dies are used.
Using this pair of pressing dies, a predetermined amount of glass lump is pressed until the distance between the molding surfaces of the pair of pressing dies reaches a predetermined value. Press molding is performed until the distance between the molding surfaces of the pair of pressing dies reaches a predetermined value. The predetermined value is, for example, in the range of 0.7 to 3.0 mm, and the allowable range of variation in the distance of the molding surface is, for example, in the range of ± 0.015 μm.

上記一対の押圧型の成形面の距離（一対の主表面の間隔）の所定の値は、好ましくは０．７５〜１．０ｍｍの範囲である。この範囲にすることにより情報記録媒体用基板の主表面形成のための研削、研磨加工を省力化することができる。   The predetermined value of the distance between the molding surfaces of the pair of pressing dies (the distance between the pair of main surfaces) is preferably in the range of 0.75 to 1.0 mm. By setting it within this range, it is possible to save labor for grinding and polishing for forming the main surface of the information recording medium substrate.

本発明の方法で製造したブランクを研削、研磨して基板を作製する過程では、必要最小限の加工で基板を得ることが望まれる。したがって、主表面部におけるブランクの厚さは基板の厚さに近いことが好ましい。その結果、ブランクの上記部分の厚さは薄いものとなる。   In the process of grinding and polishing a blank manufactured by the method of the present invention to produce a substrate, it is desired to obtain the substrate with the minimum necessary processing. Therefore, it is preferable that the thickness of the blank in the main surface portion is close to the thickness of the substrate. As a result, the thickness of the above portion of the blank is thin.

さらに、プレス成形の際には、一対の押圧型の成形面の間に所定量のガラス塊が供給され、プレスされる。供給されるガラス塊の所定量とは、所定量のガラス塊を供給するように、熔融ガラスの流量、温度、切断のタイミングなどが調整されることで定まる、設定量である。設定量は、所定(所望)の値に決められているが、実際に供給されるガラス塊の量は、供給機構等に起因して、プレス成形毎に変動する。この供給されるガラス塊の量の変動は、例えば、０．２〜５％の範囲である。実際の操業上は、ガラス塊の量の変動は、小さければ小さいほど好ましく、限りなく目的とするガラスブランクスの量に等しい量のガラス塊が供給されることが好ましい。しかし、実際には０．２〜５％の範囲の変動は許容範囲であり、本発明では、少なくともこの範囲のガラス塊の量の変動があっても、所定のガラスブランクスが製造できるように他の条件を設定する。   Further, during press molding, a predetermined amount of glass lump is supplied between the molding surfaces of the pair of pressing dies and pressed. The predetermined amount of the glass lump to be supplied is a set amount determined by adjusting the flow rate, temperature, cutting timing, etc. of the molten glass so as to supply a predetermined amount of glass lump. The set amount is determined to be a predetermined (desired) value, but the amount of glass lump that is actually supplied varies for each press forming due to the supply mechanism and the like. The variation in the amount of the glass lump supplied is, for example, in the range of 0.2 to 5%. In actual operation, the variation in the amount of glass lump is preferably as small as possible, and it is preferable to supply an amount of glass lump that is infinitely equal to the target amount of glass blanks. However, in practice, a fluctuation in the range of 0.2 to 5% is an allowable range, and in the present invention, even if there is a fluctuation in the amount of glass lump in at least this range, other glass blanks can be manufactured. Set the conditions.

軟化状態のガラスをプレスして一対の押圧型の成形面に沿って伸ばすことにより、一対の主表面を成形するが、量産における各プレス成形工程では、一対の押圧型の成形面の距離が一定になるまでガラスをプレスするとともに、前記プレスの過程で、ガラスの量の変動に応じて肉厚部成形空間へのガラスの導入量を変化させる。すなわち、上記工程でガラスの余剰分が変動しても、上記空間に逃げるガラスの量が余剰ガラスの量により自動的に決まるので、毎回、一対の押圧型の成形面の距離が一定になるまでガラスをプレスすることができる。その結果、主表面間の距離、すなわち、主表面部における厚みが一定のブランクを量産することができる。その結果、ガラス余剰量の変動があっても、一対の押圧型の成形面を互いに平行に保ったままプレスを完了することができるので、主表面間の平行度が優れたブランクを量産することもできる。   A pair of main surfaces are formed by pressing the softened glass and stretching along the forming surfaces of the pair of pressing dies. In each press forming step in mass production, the distance between the forming surfaces of the pair of pressing dies is constant. The glass is pressed until the amount of glass is introduced, and the amount of glass introduced into the thick part forming space is changed in accordance with the fluctuation of the amount of glass in the pressing process. That is, even if the surplus of the glass fluctuates in the above process, the amount of glass that escapes into the space is automatically determined by the amount of surplus glass, so that the distance between the molding surfaces of the pair of pressing dies is constant each time. Glass can be pressed. As a result, it is possible to mass-produce a blank having a constant thickness between the main surfaces, that is, the main surface portion. As a result, even if there are fluctuations in the surplus amount of glass, the press can be completed while the molding surfaces of the pair of pressing dies are kept parallel to each other, so that a blank with excellent parallelism between the main surfaces can be mass produced. You can also.

(2)主表面と外周面の成形
プレス成形の際には、軟化状態のガラス塊をプレスして一対の押圧型の対向する２つの成形面に沿ってガラスを伸ばし、伸ばしたガラスの全外周に外周規制面を転写して、ガラスブランクの一対の主表面と外周面を成形する。外周規制面の転写は、伸ばしたガラスの外周全体に欠落箇所が無いように行う。伸ばしたガラスの全外周に外周規制面を転写して、ガラスブランクの外周面を成形することで、一定の外径を有する真円度の優れたガラスブランクを量産することができる。 (2) Forming press of the main surface and outer peripheral surface When forming the softened glass lump, the glass is stretched along two opposing forming surfaces of a pair of pressing dies, and the entire outer periphery of the stretched glass The outer peripheral regulating surface is transferred to the glass blank, and a pair of main surfaces and outer peripheral surfaces of the glass blank are formed. The transfer of the outer peripheral regulation surface is performed so that there is no missing portion on the entire outer periphery of the stretched glass. By transferring the outer periphery regulating surface to the entire outer periphery of the stretched glass and molding the outer peripheral surface of the glass blank, it is possible to mass-produce glass blanks having a constant outer diameter and excellent roundness.

(3)肉厚部の成形
上記主表面と外周面の成形に引き続いて、あるいは主表面と外周面の成形に一部並行して肉厚部が成形される。但し、ガラスブランクの外縁において肉厚とならない部分は、ガラスブランクの一対の主表面の厚みと少なくとも等しい厚みを有するように、肉厚部は成形される。場所による肉厚の違いは避けられないもののガラスブランクの外縁の一部にでも所定肉厚に満たない「肉薄部」が形成されないようにガラス容量の変動における最小値を、余裕を持って想定する。肉厚部の成形は、主表面と外周面の成形の際に伸ばされたガラスを肉厚部成形用空間の一部に侵入させて行う。肉厚部成形用空間は、押圧型のキャビティ内の外周に設けられる。肉厚部成形用空間は、成形面の外周部または前記外周部の外側にあって対向する成形面の距離より大きい間隔を有する2つの面および外周規制面とから少なくとも区画される。 (3) Molding of the thick part The thick part is molded following the molding of the main surface and the outer peripheral surface or partially in parallel with the molding of the main surface and the outer peripheral surface. However, the thick portion is formed so that the portion that does not become thick at the outer edge of the glass blank has a thickness at least equal to the thickness of the pair of main surfaces of the glass blank. Although it is inevitable that the wall thickness varies depending on the location, the minimum value in the fluctuation of the glass capacity is assumed with a margin so that a “thin part” that is less than the predetermined wall thickness is not formed even at part of the outer edge of the glass blank. . The thick part is formed by allowing the glass stretched during the formation of the main surface and the outer peripheral surface to enter a part of the thick part forming space. The thick part forming space is provided on the outer periphery of the cavity of the pressing mold. The thick portion forming space is at least partitioned from the outer peripheral portion of the forming surface or two surfaces that are outside the outer peripheral portion and have a larger distance than the opposing forming surface and the outer peripheral regulating surface.

(4)ガラス塊量の変動に応じた肉厚部成形用空間へのガラス充填度の変化
上述のように、プレス成形毎に押圧型に供給されるガラス塊の量は、意図したものではないが、熔融ガラスの流出量のコントロール精度に起因して、変動する。プレス成形が一対の押圧型の成形面の距離が所定の値になるまで行われるため、主表面と外周面の成形に用いられるガラスの量は一定しており、供給されるガラス塊の量の変動に応じて変化するのは、前記肉厚部成形用空間へ導入されるガラスの量であり、結果として肉厚部のガラス量が変動する。ガラス塊の量のプレス成形毎の変動を肉厚部のガラス量が変動することで吸収し、外周規制面により形成される外径を一定に保つ。 (4) Change of glass filling degree to thick part forming space according to fluctuation of glass lump amount As described above, the amount of glass lump supplied to the pressing die for each press molding is not intended. However, it fluctuates due to the control accuracy of the outflow amount of the molten glass. Since the press molding is performed until the distance between the molding surfaces of the pair of pressing dies reaches a predetermined value, the amount of glass used for molding the main surface and the outer peripheral surface is constant, and the amount of glass lump supplied What changes according to the fluctuation is the amount of glass introduced into the thick part forming space, and as a result, the glass quantity of the thick part varies. The fluctuation of the amount of glass lump for each press forming is absorbed by the fluctuation of the glass amount in the thick part, and the outer diameter formed by the outer peripheral regulation surface is kept constant.

(5)ガラス塊の量の変動幅と肉厚部成形用空間の容量
プレス成形毎に供給するするガラス塊の量の変動幅と肉厚部成形用空間の容量は、ガラスブランクの外縁の一部にでも所定肉厚に満たない「肉薄部」が形成されず、かつ肉厚部成形用空間の全周いずれの場所でも容量を超えてガラスが充填されない範囲で設定される。尚、ガラス塊のプレス成形面への供給位置は、全ての肉厚部成形用空間において肉厚部成形用空間の容量を超えないようにプレス成形されたガラスが充填されるように、調整されることが好ましい。このような設定の下でプレス成形することで、プレス品面内で製品となる大半の面積での一定厚みと一定外径を有するガラスブランクを、バリの発生なしに製造することが可能になる。 (5) Fluctuation width of the glass lump amount and capacity of the thick part forming space The fluctuating width of the amount of glass lump supplied for each press forming and the capacity of the thick part forming space are one of the outer edges of the glass blank. The “thin portion” that is less than the predetermined thickness is not formed even in the portion, and the thickness is set in a range that does not fill the glass beyond the capacity anywhere in the circumference of the thick portion forming space. In addition, the supply position of the glass lump to the press molding surface is adjusted so that all the thick part molding spaces are filled with the press-molded glass so as not to exceed the capacity of the thick part molding spaces. It is preferable. By press-molding under such settings, it becomes possible to produce a glass blank having a constant thickness and a constant outer diameter in the majority of the area that will be the product within the surface of the pressed product without the generation of burrs. .

[肉厚部成形用空間の説明]
肉厚部成形用空間は、余剰分のガラスを逃がす空間である。この空間が型の摺動面(例えば、主表面のプレス成形面)によって囲まれている空間の場合、ガラスが侵入すると型の動きを妨げることになり、空間に侵入したガラスは摺動面によってプレスされて、結果的に、成形バリを形成してしまう。それに対して、本発明では、少なくとも一つの非摺動面により区画される空間であれば、ガラスを進入させても型の動きを妨げることはなく、成形バリができることもない。 [Explanation of thick part forming space]
The thick part forming space is a space through which excess glass is released. In the case where this space is surrounded by the sliding surface of the mold (for example, the press-molding surface of the main surface), if glass enters, the movement of the mold will be hindered. As a result, the formed burr is formed. On the other hand, in the present invention, as long as the space is defined by at least one non-sliding surface, even if glass is introduced, the movement of the mold is not hindered, and no molding burr can be formed.

プレス成形後、肉薄の平板状ガラスを冷却する過程で不均一な冷却がなされると、ガラス中に応力が発生し、反りが発生してしまう要因となる。しかし外縁に肉厚部を成形することにより、ブランクの断面二次モーメントが外縁の肉厚部がない場合に比べて増加し、反りに対する抵抗が生まれることになり、成形後のブランクの反りの程度を低減できるといった効果も得ることができる。   If non-uniform cooling is performed in the process of cooling the thin flat glass after press molding, stress is generated in the glass, which causes warping. However, by forming the thick part on the outer edge, the blanket moment of the blank increases compared to the case where there is no thick part on the outer edge, resulting in resistance to warpage and the degree of warping of the blank after forming. The effect that can be reduced can also be obtained.

上記肉厚部成形用空間の容積は、具体的には、次のように決定することができる。前述の質量Mに対し、ガラスの変動が必ずプラス方向になるよう、すなわち、ｍ＞Mになるように押圧型に供給するガラスの量を設定する。すなわち、ガラスの質量の中央値をｍ０、質量公差を±Δｍとし、供給されたガラスゴブが押圧時に平面上に拡がる際に、これまでの実績からの拡がり方の異方性に伴い、最も供給量が少ない方向でのガラス量が３６０°及んだと想定した場合の所定質量ｍ０に対する不足量をΔｍ´とすると、ｍ０−Δｍ−Δｍ´＞Mとなるようにする。次に上記空間の容積を決めるが、供給されたガラスゴブが押圧時に平面上に拡がる際に、これまでの実績からの拡がり方の異方性に伴い、最も供給量が多い方向でのガラス量が３６０°及んだと想定した場合の所定質量ｍ０に対する余剰量をΔｍ"とするとガラス余剰量がｍ０＋Δｍ＋Δｍ"−Mとなっても上記空間内にガラスを収容できるよう、すなわち、上記空間内に質量（ｍ０＋Δｍ＋Δｍ"−M）のガラスが進入してもこの空間がガラスで埋め尽くされないように空間の容積を決める。この空間をガラスが埋め尽くすと、ガラスが型と型の間に進入して摺動の妨げになり、あるいは成形バリが生じてしまう。また、押圧型の成形面同士をプレスによって所定の間隔にすることができなくなり、あるいは成形面同士を平行にできなくなるなどの問題が生じる。したがって、ガラスの進入は上記空間の一部にとどめるべきである。こうして成形される肉厚部の凸部の表面の一部または全部は、型に接触しないで成形されるので、自由曲面となる。したがって、鋭利なエッジにならないので、欠けにくいという効果を得ることができる。   Specifically, the volume of the thick part forming space can be determined as follows. The amount of glass supplied to the pressing mold is set so that the fluctuation of the glass is always in the positive direction with respect to the above-described mass M, that is, m> M. That is, the median value of the glass mass is m0, the mass tolerance is ± Δm, and when the supplied glass gob expands on a flat surface when pressed, the most supplied amount due to the anisotropy of how to expand from the past results M0−Δm−Δm ′> M, where Δm ′ is an insufficient amount with respect to the predetermined mass m0 when it is assumed that the amount of glass in a direction with less is 360 °. Next, the volume of the space is determined, but when the supplied glass gob expands on a flat surface when pressed, the amount of glass in the direction of the largest supply amount is accompanied by the anisotropy of the expansion method from the past results. When it is assumed that the surplus amount with respect to the predetermined mass m0 when it reaches 360 ° is Δm ″, the glass can be accommodated in the space even if the surplus amount of glass becomes m0 + Δm + Δm ″ −M, that is, the mass in the space When the glass of (m0 + Δm + Δm "-M) enters, the volume of the space is determined so that this space is not filled with glass. When this space is filled with glass, the glass enters and slides between the molds. This may hinder movement or cause molding burrs, and the molding surfaces of the pressing mold cannot be set at a predetermined interval by pressing, or the molding surfaces cannot be made parallel to each other. Therefore, the glass entrance should be limited to a part of the space, and part or all of the surface of the convex part of the thick part formed in this way is formed without contact with the mold, so that it is free. Therefore, since it does not become a sharp edge, an effect that it is difficult to chip can be obtained.

室温におけるガラスの密度をｄとすると、質量（ｍ０＋Δｍ＋Δｍ"−M）が室温で占める体積はｄ×（ｍ０＋Δｍ＋Δｍ"−M）となるが、ガラスの密度は室温時より高温時のほうが小さいこと、すなわち、冷却過程でガラスが体積収縮することを考慮して、ｄ×（ｍ０＋Δｍ＋Δｍ"−M）より大きめに設定する。実際、こうした計算法を目安にして空間の異なるプレス成形型を幾つか用意して所望のプレス成形が可能な型を選択する方法もあるが、一種類の成形型でも、供給するガラス容量は所定量より少なめになるような切断時間間隔設定から成形を開始し、成型品の形状を見ながら切断時間間隔を所定値に近づけていく方法がより合理的である。   Assuming that the density of the glass at room temperature is d, the volume occupied by the mass (m0 + Δm + Δm ″ −M) at room temperature is d × (m0 + Δm + Δm ″ −M), but the density of the glass is lower at the higher temperature than at room temperature, that is, In consideration of the volume shrinkage of the glass during the cooling process, it is set larger than d × (m0 + Δm + Δm "-M). Actually, several press molds with different spaces are prepared using these calculation methods as a guide. There is also a method of selecting a mold that can be used for the desired press molding, but even with one type of mold, molding is started by setting the cutting time interval so that the glass capacity to be supplied is less than the predetermined amount. It is more reasonable to make the cutting time interval close to a predetermined value while watching the above.

プレス成形では、ガラスを等方的に伸ばすことが上記要求に合致したブランクを得る上から望ましいが、前記のように現実にはガラス余剰分は必ずしも等方的に伸ばされるわけではなく、円周上の場所によりある程度肉厚の大小が生じることは避けられないとはいえ、余剰ガラスを収容する空間は等方的に設けることが望ましい。すなわち、押圧型の成形面の全外周端と外周規制面全周の間に空間を設けたプレス成形型を使用する。   In press molding, it is desirable to stretch the glass isotropically from the viewpoint of obtaining a blank that meets the above requirements, but as described above, the glass surplus is not necessarily stretched isotropically. Although it is inevitable that the wall thickness is increased to some extent depending on the location above, it is desirable to provide an isotropic space for accommodating excess glass. That is, a press mold in which a space is provided between the entire outer peripheral end of the pressing mold forming surface and the entire outer periphery regulating surface is used.

こうしたプレス成形型を用いることにより、肉厚部を全周にわたり成形することができ、上記効果を得ることができる。肉厚部を全周にわたり成形することによりブランクの断面二次モーメントをより増加させることができ、反り低減効果を高めることもできる。   By using such a press mold, the thick part can be formed over the entire circumference, and the above-described effects can be obtained. By forming the thick portion over the entire circumference, the cross-sectional secondary moment of the blank can be further increased, and the warp reduction effect can be enhanced.

押圧型の成形面の外周端と外周規制面周の間の上記空間の開口幅は全周にわたり一定であることがガラスの拡がり方の異方性が変化した場合を想定すると好ましい。   It is preferable that the opening width of the space between the outer peripheral edge of the pressing mold forming surface and the outer periphery regulating surface circumference is constant over the entire circumference, assuming the case where the anisotropy of the way the glass spreads is changed.

具体的には、肉厚部成形用空間の容量は、プレス成形毎に供給するガラス塊の量の変動やガラスの押型上での拡がり方の異方性により生じると想定される最大量のガラスが供給される円周上の方向においても、肉厚部成形用空間においてガラスが占める断面積の１１０％〜２００％の断面積を持つように設定されることが好ましい。１１０％未満では、ガラスの押型上での拡がり方の異方性の変化により、円周内のどこかで、空間の全てをガラスが埋め尽くす場所が発生しガラスを挟み込むことにより、成形面同士を平行にできなくなるリスクが高まるという問題が生じる可能性があり、また２００％を超えても大きな弊害は無いが、そこまでの余裕空間は現実的には必要ない。   Specifically, the capacity of the thick part forming space is the maximum amount of glass that is assumed to be caused by fluctuations in the amount of glass lump supplied at each press forming and anisotropy of how to spread on the glass mold. Also in the direction on the circumference to which is supplied, it is preferably set so as to have a cross-sectional area of 110% to 200% of the cross-sectional area occupied by the glass in the thick part forming space. If it is less than 110%, due to a change in the anisotropy of how the glass spreads on the mold, a place where the glass fills up all of the space occurs somewhere in the circumference, and the glass is sandwiched between the molding surfaces. There is a possibility that the risk that the two cannot be made parallel increases, and even if it exceeds 200%, there is no serious adverse effect.

[押圧型]
本発明において、プレス成形に用いる一対の押圧型は、少なくとも外周規制面と対向する成形面からなるキャビティを有し、このキャビティの外周に肉厚部成形用空間を有する。 [Pressing type]
In the present invention, the pair of pressing dies used for press molding has a cavity formed of a molding surface facing at least the outer periphery regulating surface, and has a thick portion molding space on the outer periphery of the cavity.

具体的には、一対の押圧型は、一方の押圧型が外周規制面を備える、上型および下型の一対の押圧型であってもよいし、外周規制面を備えない上型および下型の一対の押圧型と、それとは別体であって内周面が外周規制面として機能する胴型との組み合わせであってもよい。一対の押圧型を含むプレス成形に使用する型を、以下、プレス成形型と呼ぶことにする。図1〜4に基づいて、プレス成形型の説明をする。図1〜4に示すプレス成形型は、胴型を用いない、一対の押圧型のみからなるものである。   Specifically, the pair of pressing molds may be a pair of pressing molds of an upper mold and a lower mold in which one pressing mold includes an outer peripheral regulating surface, or an upper mold and a lower mold that do not include an outer circumferential regulating surface. A combination of a pair of pressing molds and a body mold that is a separate body and whose inner peripheral surface functions as an outer peripheral regulating surface may be used. A die used for press molding including a pair of pressing dies is hereinafter referred to as a press molding die. The press mold will be described with reference to FIGS. The press mold shown in FIGS. 1 to 4 is composed of only a pair of pressing dies without using a body mold.

図1に示すプレス成形型は、上型１０および下型２０の一対の押圧型からなり、上型１０のプレス面３０は平坦であり、プレス面の外周は、プレス面とほぼ垂直な外周規制面５０と接続する。下型２０のプレス面４０は、主表面は平坦であるが、中心部に凹部４０ａを有し、プレス面の外周は、一段低い段差部４０ｂを有する。上型１０のプレス面３０の外周３０ａ付近と外周規制面５０および下型の段差部４０ｂが、余剰分のガラスを逃がすための肉厚部成形用空間６０を形成する。   The press mold shown in FIG. 1 is composed of a pair of pressing dies of an upper die 10 and a lower die 20, the press surface 30 of the upper die 10 is flat, and the outer periphery of the press surface is an outer peripheral restriction substantially perpendicular to the press surface. Connect with surface 50. The press surface 40 of the lower mold 20 has a flat main surface, but has a recess 40a at the center, and the outer periphery of the press surface has a step 40b that is one step lower. The vicinity of the outer periphery 30a of the press surface 30 of the upper die 10, the outer periphery regulating surface 50, and the step portion 40b of the lower die form a thick portion forming space 60 for allowing excess glass to escape.

図2に示すプレス成形型は、上型１１および下型２１の一対の押圧型からなり、下型２１のプレス面４１は平坦であり、プレス面４１の外周は、プレス面とほぼ垂直な外周規制面５１と接続する。上型１１のプレス面３１は、主表面は平坦であるが、中心部に凹部３１ａを有し、プレス面の外周は、一段高い段差部３１ｂを有する。下型のプレス面４１の外周４１ａ付近と外周規制面５１および上型の段差部３１ｂが、余剰分のガラスを逃がすための肉厚部成形用空間６１を形成する。   The press mold shown in FIG. 2 includes a pair of pressing dies of an upper die 11 and a lower die 21. The press surface 41 of the lower die 21 is flat, and the outer periphery of the press surface 41 is an outer periphery substantially perpendicular to the press surface. Connect to the restriction surface 51. The press surface 31 of the upper die 11 has a flat main surface, but has a recess 31a at the center, and the outer periphery of the press surface has a stepped portion 31b that is one step higher. The vicinity of the outer periphery 41a of the lower die press surface 41, the outer periphery regulating surface 51, and the upper die step portion 31b form a thick portion forming space 61 for allowing excess glass to escape.

図3に示すプレス成形型は、図1に示すプレス成形型と類似するが、上型１２および下型２２の一対の押圧型からなり、下型２２の段差部４２ｂがプレス面に近い部分に凹部４２ｃをする。
凹部の機能を説明する下型の段差部４２ｂ、凹部４２ｃ、および外周規制面５２が、余剰分のガラスを逃がすための肉厚部成形用空間６２を形成する。 The press mold shown in FIG. 3 is similar to the press mold shown in FIG. 1, but is composed of a pair of pressing molds of an upper mold 12 and a lower mold 22, and the step portion 42b of the lower mold 22 is located near the press surface. A recess 42c is formed.
The lower mold step 42b, the recess 42c, and the outer periphery regulating surface 52, which explain the function of the recess, form a thick part forming space 62 for allowing excess glass to escape.

図4に示すプレス成形型は、図2に示すプレス成形型と類似するが、上型１３および下型２３の一対の押圧型からなり、上型１３の段差部３３ｂがプレス面に近い部分に凹部３３ｃをする。
凹部の機能を説明する上型の段差部３３ｂ、凹部３３ｃ、および外周規制面５３が、余剰分のガラスを逃がすための肉厚部成形用空間６３を形成する。 The press mold shown in FIG. 4 is similar to the press mold shown in FIG. 2, but is composed of a pair of pressing molds of an upper mold 13 and a lower mold 23, and the step portion 33b of the upper mold 13 is located near the press surface. A recess 33c is formed.
The upper mold step portion 33b, the concave portion 33c, and the outer peripheral regulating surface 53, which explain the function of the concave portion, form a thick portion forming space 63 for allowing excess glass to escape.

図5に示すプレス成形型は、上型１４および下型２４の一対の押圧型からなり、上型１４のプレス面３４は平坦であり、プレス面３４の外周には、プレス面より一段高い段差部３４ａを有し、この段差部３４ａのさらに外周部が外周規制面５４と接続する。下型２４のプレス面４４は、主表面は平坦であるが、中心部に凹部４４ａを有し、プレス面４４の外周は、一段低い段差部４４ｂを有する。上型の段差部３４ａと外周規制面５４および下型の段差部４４ｂが、余剰分のガラスを逃がすための肉厚部成形用空間６４を形成する。   The press mold shown in FIG. 5 is composed of a pair of pressing dies of an upper die 14 and a lower die 24, the press surface 34 of the upper die 14 is flat, and the outer periphery of the press surface 34 is a step higher than the press surface. 34a, and the outer peripheral portion of the stepped portion 34a is connected to the outer peripheral regulating surface 54. The press surface 44 of the lower mold 24 has a flat main surface, but has a recess 44a at the center, and the outer periphery of the press surface 44 has a stepped portion 44b that is one step lower. The upper mold step portion 34a, the outer peripheral regulation surface 54, and the lower mold step portion 44b form a thick portion forming space 64 for allowing excess glass to escape.

図6に示すプレス成形型は、上型１５および下型２５の一対の押圧型からなり、下型２５のプレス面４５は平坦であるが、中心部に凹部４５ａを有し、プレス面の外周は、一段低い段差部４５ｂを有する。さらに、この段差部３５ｂのさらに外周部が外周規制面５５と接続する。上型１５のプレス面３５は、主表面は平坦であるが、中心部に凹部３５ａを有し、プレス面の外周は、一段高い段差部３５ｂを有する。下型２５の段差部４５ｂと外周規制面５５および上型の段差部３５ｂが、余剰分のガラスを逃がすための肉厚部成形用空間６５を形成する。   The press mold shown in FIG. 6 includes a pair of pressing dies, that is, an upper die 15 and a lower die 25. The press surface 45 of the lower die 25 is flat, but has a recess 45a at the center, and the outer periphery of the press surface. Has a step 45b that is one step lower. Further, the outer peripheral portion of the stepped portion 35 b is connected to the outer peripheral regulating surface 55. The press surface 35 of the upper die 15 has a flat main surface, but has a recess 35a at the center, and the outer periphery of the press surface has a step 35b that is one step higher. The step portion 45b of the lower mold 25, the outer peripheral regulating surface 55, and the step portion 35b of the upper mold form a thick portion forming space 65 for allowing excess glass to escape.

上記図1〜4の型構造は、型閉めした状態で上型と下型とが直接当接する構造を有する。このような構造とすることにより、上型が下型に対して、あるいは下型が上型に対して傾かなくなり、２つの主表面の平行度が高いブランクを得ることができる。また、上下型の成形面の距離も常に一定になるので、肉厚公差を小さくすることもできる。   The mold structure shown in FIGS. 1 to 4 has a structure in which the upper mold and the lower mold are in direct contact with each other when the mold is closed. By setting it as such a structure, the upper mold | type does not incline with respect to a lower mold | type, or a lower mold | type does not incline with respect to an upper mold | type, and a blank with high parallelism of two main surfaces can be obtained. Further, since the distance between the molding surfaces of the upper and lower molds is always constant, the thickness tolerance can be reduced.

さらに、図1、2に示す金型構造には、ブランクの片面全体を平坦に成形し、この面を研削時の基準面にできるメリットがある。ただし、このようなブランクには次のようなデメリットもある。研削は２つの研削盤にブランクを挟んでブランクを両面から削るが、片面全体が平坦なブランクでは、さほど削る必要のない平坦な面も同時に削れてしまう。   Furthermore, the mold structure shown in FIGS. 1 and 2 has an advantage that one side of the blank is formed flat and this surface can be used as a reference surface during grinding. However, such blanks also have the following disadvantages. In grinding, a blank is sandwiched between two grinders and the blank is shaved from both sides. However, if the blank is flat on one side, a flat surface that does not need to be shaved so much is shaved at the same time.

それに対して図5、6に示す金型構造を用いて成形したブランクでは、上記のようなデメリットを解消する。例えば、図5では上型側の肉厚部成形用空間にはガラスが１００％充填され、下型側の肉厚部成形用空間にはガラスが容量変動に応じて適度に充填される。こうすることにより、肉厚部の上型側表面は型転写面となり、研削時に基準面として利用することができる。図6は、図5と逆で、肉厚部の下型側表面を研削基準面として利用することができる。   In contrast, blanks molded using the mold structure shown in FIGS. 5 and 6 eliminate the above disadvantages. For example, in FIG. 5, the thick part forming space on the upper mold side is 100% filled with glass, and the thick part forming space on the lower mold side is filled appropriately with the capacity variation. By doing so, the upper mold side surface of the thick part becomes a mold transfer surface, which can be used as a reference surface during grinding. FIG. 6 is opposite to FIG. 5 and the lower mold side surface of the thick part can be used as a grinding reference surface.

［成形面中央部に設けた凹部についての説明］
プレス成形によって成形面中央部の凹部がガラスに転写されて成形品主表面に凸部が形成されることが好ましい。この中央部の凸部高さは外縁部の凸部高さより常に高くなるよう設定することが望ましい。プレス成形されたガラスブランクはプレス成形時及びその後の急冷により発生した歪みを緩和するために徐冷する必要があるが、徐冷に必要な徐冷装置（徐冷炉）の面積を節約するためにガラスブランクは通常、数枚ないし十数枚積み重ねられた状態で徐冷することが多い。その際積み重ねられたガラスブランク同士がわずかな反りにより不均一に接触していると、接触しているところと接触していないところで冷却時に冷却条件が大きく異なる結果を生み、それが平面度の更なる悪化の原因となる。ここでガラスブランクの中央部の凸部高さが外縁部の凸部高さより十分高ければ、最終的に製品とならない中央凸部以外では積み重ねられたガラスブランク同士が接触することはなく、変形しやすい肉薄部は互いに空気層により確実に隔てられるため、徐冷時に場所による大きな温度条件の差が生じることが避けられ、徐冷課程での平面度の悪化はほとんど防止できる。中央凸部は直径に対しもともと十分な肉厚を持つため、場所による冷却条件の違いが発生してもその変形量は無視できるレベルとなる。 [Explanation about the recess provided in the center of the molding surface]
It is preferable that the concave portion at the center of the molding surface is transferred to glass by press molding to form a convex portion on the main surface of the molded product. It is desirable that the height of the convex portion at the center is set to be always higher than the height of the convex portion at the outer edge. The press-molded glass blank needs to be gradually cooled in order to relieve the distortion generated during the press molding and the subsequent rapid cooling, but it is necessary to reduce the area of the slow cooling device (slow cooling furnace) necessary for slow cooling. Usually, blanks are gradually cooled in a state where several to dozens are stacked. In this case, if the stacked glass blanks are in non-uniform contact due to slight warpage, the cooling conditions will vary greatly during cooling where they are in contact with each other, and this will cause an increase in flatness. Cause worsening. If the convex part height of the central part of the glass blank is sufficiently higher than the convex part height of the outer edge part, the stacked glass blanks do not come into contact with each other except for the central convex part which does not finally become a product. Since the easy thin portions are reliably separated from each other by the air layer, it is possible to avoid a large difference in temperature conditions depending on the place during slow cooling, and it is possible to almost prevent deterioration of flatness during the slow cooling process. Since the central convex portion originally has a sufficient thickness with respect to the diameter, the amount of deformation is negligible even if the cooling condition varies depending on the location.

ガラスブランク主表面の中央凸部高さが高過ぎる場合、上記のようにガラスブランクを複数枚積載した時、物理的に不安定になる、また、使用ガラス材料が多くなり、研削、研磨などで除去するガラスが増えて廃棄物が増え、ガラスの熔解など生産時に消費したエネルギーが無駄になってしまうなどの弊害が生じる。一方、中央凸部が低すぎる場合、円周方向で高さの異なる外縁の凸部でガラスブランク同士が重なるため中央凸部が高すぎる場合以上に積載時に物理的に不安定になる弊害が生じる。   If the height of the central convex part of the glass blank main surface is too high, it becomes physically unstable when multiple glass blanks are stacked as described above, and more glass material is used, resulting in grinding, polishing, etc. The amount of glass to be removed increases and waste increases, resulting in problems such as glass melting and waste of energy consumed during production. On the other hand, if the central convex portion is too low, the glass blanks overlap with each other at the outer circumferential convex portions having different heights in the circumferential direction, so that there is a problem that the paper becomes physically unstable when loading more than when the central convex portion is too high. .

外縁部の凸部高さは流出する熔融ガラスの流量変動や溶融ガラスの平面方向への伸びやすさに伴い変動するので、これらの要因を勘案して中央凸部高さを設定すればよい。図7に垂直断面を図示したガラスブランク１００では、熔融ガラスの流量変動に合わせて、プレス成形に供するガラスの量が最大になったとき、外縁凸部１１０の最大高さが０．５ｍｍになると想定し、余裕を見て中央凸部１２０高さを外縁凸部の最大高さ０．５ｍｍにさらに０．５ｍｍを加えて１ｍｍとしている。   Since the height of the convex portion of the outer edge portion varies with the flow rate fluctuation of the molten glass flowing out and the easiness of the molten glass to extend in the plane direction, the central convex portion height may be set in consideration of these factors. In the glass blank 100 whose vertical cross section is shown in FIG. 7, when the amount of glass used for press molding is maximized in accordance with the flow rate fluctuation of the molten glass, the maximum height of the outer edge convex portion 110 is 0.5 mm. Assuming a margin, the height of the central protrusion 120 is set to 1 mm by adding 0.5 mm to the maximum height of the outer edge protrusion 0.5 mm.

なお、ブランク中央の突起は両面に出ても（図５、６）、片面側のみに出ても（図１〜４）（後工程で最初に中央部をくり抜く（中心孔開け加工）ので、支障はない。   Even if the protrusion at the center of the blank appears on both sides (FIGS. 5 and 6) or only on one side (FIGS. 1 to 4) (because the central part is first hollowed out in the subsequent process (center hole drilling process), There is no hindrance.

但し、本発明の好ましい態様は、一方の主表面を平坦とし、他方の主表面の外縁に凸部を設けて外縁を肉厚にする方法である。一方の主表面を平坦にすることで、平坦な主表面を基準面として他方の主表面を平行かつ平坦に研削し、両主表面間に平行度、平坦度を高めることができる。もう一方の主表面の外縁には余剰ガラスによって形成される凸部を成形する。この凸部は研削基準面側にないので、研削時の上記操作を妨げることもない。   However, a preferred embodiment of the present invention is a method in which one main surface is made flat and a convex portion is provided on the outer edge of the other main surface so that the outer edge is thick. By flattening one main surface, the other main surface can be ground in parallel and flat with the flat main surface as a reference plane, and the parallelism and flatness between both main surfaces can be increased. A convex portion formed of excess glass is formed on the outer edge of the other main surface. Since this convex part is not on the grinding reference surface side, the above operation during grinding is not hindered.

［プレス成形］
本発明における軟化状態のガラスとしては、熔融ガラス塊である場合と予備成形されたガラス塊を加熱、軟化したものである場合とがある。 [Press molding]
The softened glass in the present invention may be a molten glass lump or a pre-formed glass lump heated and softened.

熔融ガラス塊を用いる場合、一定流量でパイプから流出する熔融ガラス流の下端を押圧型の成形面で受け、その後にパイプ流出口下方で熔融ガラス流を切断し、成形面上に熔融ガラス塊を得る方法を用いる。プレスによりガラスを押圧型成形面上に等方的に伸ばすため、一方の押圧型の成形面中央に熔融ガラス塊を供給してプレス成形することが望ましい。例えば、一対の押圧型を上型と下型で構成し、下型成形面に熔融ガラス塊を供給する場合、前述の操作を行い、下型成形面の中央に熔融ガラス塊を供給する。   When using a molten glass lump, the lower end of the molten glass flow flowing out of the pipe at a constant flow rate is received by the pressing mold forming surface, and then the molten glass flow is cut below the pipe outlet and the molten glass lump is placed on the forming surface. Use the method to obtain. In order to stretch the glass isotropically on the pressing mold forming surface by pressing, it is desirable to supply the molten glass lump to the center of the forming surface of one pressing mold and press mold. For example, when a pair of pressing dies are composed of an upper mold and a lower mold and the molten glass lump is supplied to the lower mold forming surface, the above-described operation is performed to supply the molten glass lump to the center of the lower mold forming surface.

熔融ガラスの流出スピードを一定に保ち、熔融ガラス流の切断を一定の時間間隔で行えば、ガラスの変動量を少なく抑えることができ、その上で本発明を適用することが望ましい。   If the outflow speed of the molten glass is kept constant and the molten glass flow is cut at regular time intervals, the amount of fluctuation of the glass can be suppressed, and it is desirable to apply the present invention.

複数対の押圧型を用いてプレス成形工程を繰り返すことで、連続的に流出する熔融ガラスから次々とブランクを成形することができる。例えば、ターンテーブル上に複数個の下型を配置し、ターンテーブルをインデックス回転させる。熔融ガラスを流出するパイプの下方に下型が停留する間に熔融ガラス塊の供給を行い、次の停留位置に下型を移動して、当該停留位置の上方に待機する上型を下降してプレス成形する。プレス終了後、プレス成形品を上型から離型し、次の停留位置へと成形品を載せた下型を移送する。こうして、プレス成形品に取り出しのための力を加えても変形しない温度にまで成形品を冷却した後、下型から取り出してアニールする。こうした操作を複数の下型で順次、１セクションずつずらしながら並行して行うことにより、ブランクを量産する。   By repeating the press molding process using a plurality of pairs of pressing dies, blanks can be molded one after another from the molten glass that continuously flows out. For example, a plurality of lower molds are arranged on the turntable, and the turntable is index-rotated. While the lower mold is stopped below the pipe that flows out of the molten glass, the molten glass lump is supplied, the lower mold is moved to the next stop position, and the upper mold waiting on the stop position is lowered. Press molding. After the press is completed, the press-molded product is released from the upper mold, and the lower mold on which the molded product is placed is transferred to the next stop position. In this way, after cooling the molded product to a temperature at which it does not deform even when a force for taking out is applied to the press-molded product, it is taken out from the lower mold and annealed. A blank is mass-produced by sequentially performing such operations on a plurality of lower molds while shifting one section at a time.

なお、熔融ガラスを供給する押圧型が過熱するとガラスと融着してしまうため、少なくとも熔融ガラスを供給する押圧型成形面を冷却することが望ましい。その一方で押圧型の温度が低すぎるとプレスによってガラスを押し広げる前にガラスが硬くなり、ガラスを伸ばすことができなくなる。こうした不具合を解消するため、押圧型を加熱して、その温度を適正範囲に保つようにしてもよい。各型とも適正な温度になるよう型温を制御することが望ましい。   In addition, since it will fuse | melt with glass if the press type | mold which supplies molten glass overheats, it is desirable to cool the press type | mold molding surface which supplies at least molten glass. On the other hand, if the temperature of the pressing mold is too low, the glass becomes hard before the glass is spread by the press, and the glass cannot be stretched. In order to eliminate such a problem, the pressing mold may be heated to keep the temperature within an appropriate range. It is desirable to control the mold temperature so that each mold has an appropriate temperature.

このように型温を制御しても、熔融ガラス塊を押圧型成形面に供給してプレスする場合、成形するという目的と焼き付きを防ぐ上からも型表面温度はガラス転移点近傍に設定せざるを得ず、型に最初に接触したガラスの部位から、粘度が急上昇を開始してある程度時間経過すると圧力を加えても薄く伸びにくくなる。こうした不具合を回避するには、熔融ガラス塊の供給位置に対応する部分を肉厚に成形することが好ましい。肉薄部ではガラス表面と成形面とが接触すると、ガラス内部まで急冷されて薄肉部全体の粘度が急上昇するが、ガラスの熱伝導度は小さいので肉厚部ではガラス内部の粘度は比較的低く保たれる。したがって、熔融ガラス塊の供給位置に対応する部分の下型側もしくは対向する上型面側を肉厚にすることにより、それ以外の部分ではよりガラスを薄く等方的に押し広げることができる。したがって、こうした成形のためには、成形面中央部下型側ないしは上型側に凹部を設けた押圧型を用いることが好ましく、前記凹部にガラスを導入することで中央を肉厚にして熱量を持たせることが好ましい。   Even if the mold temperature is controlled in this way, when the molten glass lump is supplied to the pressing mold forming surface and pressed, the mold surface temperature must be set near the glass transition point from the viewpoint of forming and preventing seizure. After a certain time has passed since the viscosity started to rise rapidly from the part of the glass that first contacted the mold, it became difficult to stretch thinly even if pressure was applied. In order to avoid such inconveniences, it is preferable to form a portion corresponding to the supply position of the molten glass lump to a thickness. In the thin part, when the glass surface comes into contact with the molding surface, the inside of the glass is rapidly cooled and the viscosity of the whole thin part rises rapidly.However, since the thermal conductivity of the glass is small, the viscosity inside the glass is kept relatively low in the thick part. Be drunk. Therefore, by thickening the lower mold side or the opposed upper mold surface side of the part corresponding to the molten glass lump supply position, the glass can be more thinly and isotropically spread in the other parts. Therefore, for such molding, it is preferable to use a pressing die provided with a recess on the lower mold side or upper mold side of the molding surface. By introducing glass into the recess, the center is thickened and has a heat quantity. Preferably.

このような成形では、一方の主表面を平坦とし、他方の主表面の外縁と中央部に凸部を設けて外縁と中心部を肉厚にすることが好ましい。こうして成形したブランクの主表面の一方は平坦であり、研削基準面に適している。   In such molding, it is preferable that one main surface is flat, and convex portions are provided on the outer edge and the central portion of the other main surface so that the outer edge and the central portion are thick. One of the main surfaces of the blank thus formed is flat and suitable as a grinding reference surface.

具体例としては、成形面の中央部に凹部を、外縁部に外縁凹部を設けた上型と、平坦な成形面を有する下型とでプレス成形すると、下側の主表面は平坦、上側の主表面は中央部が凸、外縁部も凸で中央部と外縁部の間に平坦部が形成される。こうした場合、下側主表面と上側主表面の平坦部は互いに平行であって、下側主表面と上側主表面の平坦部の距離がブランクの肉厚となる。   As a specific example, when press molding is performed with an upper mold having a recess at the center of the molding surface and an outer edge recess at the outer edge and a lower mold having a flat molding surface, the lower main surface is flat and the upper The main surface is convex at the center, the outer edge is also convex, and a flat portion is formed between the center and the outer edge. In such a case, the flat portions of the lower main surface and the upper main surface are parallel to each other, and the distance between the flat portions of the lower main surface and the upper main surface is the blank thickness.

他の例としては、成形面の中央部に凹部を、外縁部に外縁凹部を設けた下型と、平坦な成形面を有する上型とでプレス成形すると、上側の主表面は平坦、下側の主表面は中央部が凸、外縁部も凸で中央部と外縁部の間に平坦部が形成される。こうした場合、上側主表面と下側主表面の平坦部は互いに平行であって、上側主表面と下側主表面の平坦部の距離がブランクの肉厚となる。   As another example, when press molding with a lower mold having a recess at the center of the molding surface and an outer edge recess at the outer edge and an upper mold having a flat molding surface, the upper main surface is flat and lower As for the main surface, the center part is convex, the outer edge part is also convex, and a flat part is formed between the center part and the outer edge part. In such a case, the flat portions of the upper main surface and the lower main surface are parallel to each other, and the distance between the flat portions of the upper main surface and the lower main surface is the blank thickness.

上記好ましい態様ではないが、外縁部の凸部と中央部の凸部とが互いに反対側になるようなブランクも本発明によって得られる例である。   Although it is not the said preferable aspect, the blank from which the convex part of an outer edge part and the convex part of a center part become a mutually opposite side is also an example obtained by this invention.

予備成形したガラスを加熱、軟化してプレス成形する場合、例えば、予め一定の外径、厚みを有する円盤状のガラスを加工し、このガラスを軟化用の断熱性能の高いセラミック製皿の上で均一な温度分布になるよう加熱、軟化する。ガラスが軟化したところでプレス用の型に移し替えプレス成形する。この方法では、連続流出する熔融ガラスを所定容量になるまで時間をかけて低温のプレス下型上で受ける場合と異なり、ガラス塊全体の温度ばらつきが小さくかつ、よりプレスに適した粘度でプレスすることができる。したがって、ガラスを供給する部分に相当する位置を肉厚に成形しなくても良好な成形が容易となる。その一方、予備成形、加工が必要になり、ガラスを成形面の中央に正確に配置する操作も面倒という問題がある。   When pre-molded glass is heated and softened and press-molded, for example, a disk-shaped glass having a predetermined outer diameter and thickness is processed in advance, and this glass is placed on a ceramic plate with high heat insulation performance for softening. Heat and soften to have a uniform temperature distribution. When the glass is softened, it is transferred to a press mold and press-molded. In this method, unlike the case where the molten glass that continuously flows out is received on a low-temperature press mold until it reaches a predetermined capacity, the temperature variation of the entire glass lump is small and the viscosity is more suitable for pressing. be able to. Therefore, good molding is facilitated even if the position corresponding to the portion for supplying glass is not molded thick. On the other hand, preliminary molding and processing are required, and there is a problem that the operation of accurately arranging the glass at the center of the molding surface is troublesome.

［情報記録媒体用基板の製造方法］
本発明の情報記録媒体用基板の製造方法は、上記方法で量産したブランクの２つの主表面を研削する工程、研削した主表面を研磨する工程、ブランクの外周面を基準に中心孔開け位置を定め、中心孔開け加工する工程を有する情報記録媒体用基板の製造方法である。 [Method of manufacturing substrate for information recording medium]
The information recording medium substrate manufacturing method of the present invention includes a step of grinding two main surfaces of a blank mass-produced by the above method, a step of polishing the ground main surface, and a center drilling position based on the outer peripheral surface of the blank. This is a method for manufacturing a substrate for information recording media, which includes a step of defining and central hole drilling.

上記方法で量産されるブランクは、外周面が外周規制面の転写成形面であるため、外周規制面を円筒形状にしておけば、真円度の優れた略円盤状のブランクであるため、外径、一対の主表面の平坦部の間隔がともに一定となる。   Blanks mass-produced by the above method are transfer-molded surfaces whose outer peripheral surfaces are outer peripheral restricting surfaces, so if the outer peripheral restricting surfaces are made into a cylindrical shape, they are substantially disk-shaped blanks with excellent roundness. Both the diameter and the distance between the flat portions of the pair of main surfaces are constant.

こうしたブランクでは中心孔開け位置を幾何学的に円の中心とすることができるので、特許文献３に記載されているように重心位置を求める工程が不要となる。しかも、外周面を加工せず、外周規制面の転写成形面を基板の外周面としてそのまま使うことができるので、外周加工を省略することができる。   In such a blank, the center hole position can be geometrically set to the center of the circle, so that the step of obtaining the position of the center of gravity is not required as described in Patent Document 3. In addition, since the outer peripheral surface is not processed and the transfer molding surface of the outer peripheral regulating surface can be used as it is as the outer peripheral surface of the substrate, the peripheral processing can be omitted.

本発明の好ましい態様は、プレス成形で成形した平坦な主表面を基準にして、主表面の研削を行う上記製造方法である。ブランクの形状は前述のように他種多様であるが、本態様は、平坦な主表面を研削基準面として、基準面に対して平行に他方の主表面を研削し、両主表面の平坦度、平行度を高める研削を進め、その後、両主表面の平滑性を高める研磨を行う。   A preferred embodiment of the present invention is the above manufacturing method in which the main surface is ground with reference to a flat main surface formed by press molding. As described above, the shape of the blank is various, but this embodiment uses the flat main surface as a grinding reference surface, grinds the other main surface parallel to the reference surface, and flatness of both main surfaces. Then, grinding is performed to increase parallelism, and then polishing is performed to improve the smoothness of both main surfaces.

こうして中心孔を備える情報記録媒体用基板を作製する。
得られた基板は必要に応じて化学強化してもよい。また、ブランクを熱処理して結晶化し、得られた略円盤状の結晶化ガラスを研削、研磨、中心孔開けを行って基板としてもよい。 Thus, an information recording medium substrate having a central hole is produced.
The obtained substrate may be chemically strengthened as necessary. Alternatively, the blank may be heat treated to crystallize, and the obtained substantially disk-shaped crystallized glass may be ground, polished, and center-drilled to form a substrate.

本発明で使用するガラスは特に限定されないが、アルミノシリケートガラスやアルミノボロシリケートガラス、無アルカリガラスなどが好適である。化学強化を行う場合は、化学強化可能なアルカリ金属含有ガラス（好ましくは、リチウム含有ガラス、ナトリウム含有ガラス）を用い、結晶化ガラス基板を作るには、均質かつ微細な結晶相の析出が可能なガラスを用いる。これらのガラスは広く提案されているものがいくつもあるので、それら公知のものを適宜使用すればよい。   The glass used in the present invention is not particularly limited, but aluminosilicate glass, aluminoborosilicate glass, alkali-free glass and the like are suitable. When chemical strengthening is performed, alkali metal-containing glass (preferably, lithium-containing glass or sodium-containing glass) that can be chemically strengthened is used, and in order to produce a crystallized glass substrate, a homogeneous and fine crystal phase can be precipitated. Glass is used. Since many of these glasses are widely proposed, those known ones may be used as appropriate.

［情報記録媒体の製造方法］
本発明の情報記録媒体の製造方法は、上記方法で作製した基板上に情報記録層を含む膜を形成する工程を有する情報記録媒体の製造方法である。ここで情報記録媒体は、上記の情報記録媒体用基板上に情報記録層を含む多層膜を有するものである。情報記録媒体は記録方式から磁気記録媒体、光磁気記録媒体、光ディスクなどに大別されるが、磁気記録媒体に特に好適である。以下、磁気記録媒体を例にとり情報記録媒体 について詳述する。 [Method of manufacturing information recording medium]
The method for producing an information recording medium of the present invention is a method for producing an information recording medium including a step of forming a film including an information recording layer on a substrate produced by the above method. Here, the information recording medium has a multilayer film including an information recording layer on the information recording medium substrate. Information recording media are roughly classified into magnetic recording media, magneto-optical recording media, optical discs, and the like, depending on the recording method, and are particularly suitable for magnetic recording media. Hereinafter, the information recording medium will be described in detail by taking a magnetic recording medium as an example.

前記基板の主表面上に形成される情報記録層（磁気記録層）を含む多層膜の構造としては、例えば、磁気記録層のほか下地層、保護層、潤滑層などがある。各層は目的とする仕様に応じた組成、膜構成をとる。磁気記録層は磁性層あるいは磁性層と非磁性層によって構成される。磁性層としてはＣｏを主成分とする合金が好適である。下地層は磁性層に応じて選択されるが、Ｃｏ合金の磁性層の場合にはＣｒを含む合金（例えば、ＣｒＷを含む合金、ＣｒＭｏを含む合金、ＣｒＶを含む合金など）が好ましい。保護層としては炭素保護膜を、潤滑層としてはパーフルオロポリエーテルをフレオン系溶媒などで希釈したものを塗布して形成したものを例示することができる。上記下地層、磁性層、非磁性層、保護層の成膜はスパッタリング成膜が好ましい。上記構成は、長手方向磁気記録媒体に好適である。   Examples of the structure of the multilayer film including the information recording layer (magnetic recording layer) formed on the main surface of the substrate include an underlayer, a protective layer, and a lubricating layer in addition to the magnetic recording layer. Each layer has a composition and a film configuration according to the intended specification. The magnetic recording layer is composed of a magnetic layer or a magnetic layer and a nonmagnetic layer. As the magnetic layer, an alloy containing Co as a main component is suitable. The underlayer is selected according to the magnetic layer, but in the case of a Co alloy magnetic layer, an alloy containing Cr (for example, an alloy containing CrW, an alloy containing CrMo, an alloy containing CrV, etc.) is preferable. Examples of the protective layer include a carbon protective film, and examples of the lubricating layer formed by applying a perfluoropolyether diluted with a freon solvent or the like. The underlayer, magnetic layer, nonmagnetic layer, and protective layer are preferably formed by sputtering. The above configuration is suitable for the longitudinal magnetic recording medium.

長手方向の磁気記録媒体では、基板の加熱を成膜工程の前に行うことが好ましい。垂直磁気記録媒体では、例えば基板上にシード層、軟磁性層、非磁性層、磁性層（磁気記録層）、保護層、潤滑層を設ける。赤外線照射加熱は、軟磁性層成膜後、非磁性層成膜前の時点、あるいは、磁性層成膜後、保護層成膜前の時点で行うことが好ましい。このような加熱により磁気記録の特性が向上し、軟磁性層の磁化異方性を揃えることができる。なお、加熱時に磁場を印加してもよい。   In the longitudinal magnetic recording medium, the substrate is preferably heated before the film forming step. In a perpendicular magnetic recording medium, for example, a seed layer, a soft magnetic layer, a nonmagnetic layer, a magnetic layer (magnetic recording layer), a protective layer, and a lubricating layer are provided on a substrate. The infrared irradiation heating is preferably performed after the soft magnetic layer is formed and before the nonmagnetic layer is formed, or after the magnetic layer is formed and before the protective layer is formed. Such heating improves the characteristics of magnetic recording and makes it possible to align the magnetization anisotropy of the soft magnetic layer. A magnetic field may be applied during heating.

シード層としては、Ｔｉ合金、Ｃｒ合金を、軟磁層としてはＦｅＴａＣ、ＦｅＣｏＢ、ＣｏＴａＺｒ、ＣｏＮｂＺｒ、ＮｉＦｅ、ＦｅＡｌＳｉを、非磁性層としてはＴｉ系合金、ＮｉＴａＺｒを、磁性層としては、Ｃｏ系合金、保護層としてはカーボン、潤滑層としては上記と同じ潤滑層を例示できる。   The seed layer is Ti alloy, Cr alloy, the soft magnetic layer is FeTaC, FeCoB, CoTaZr, CoNbZr, NiFe, FeAlSi, the nonmagnetic layer is Ti-based alloy, NiTaZr, and the magnetic layer is Co-based alloy, Examples of the protective layer include carbon, and examples of the lubricating layer include the same lubricating layer as described above.

以下、本発明を実施例によりさらに説明する。   Hereinafter, the present invention will be further described by examples.

図1に示した垂直断面形状（成形型の中心軸を含む断面）を有する成形型を用いて熔融ガラス塊をプレス成形する工程を繰り返し、円盤状のガラスブランクを試験的に量産した。得られたガラスブランクの垂直断面形状（中心軸を含む断面）を図7に示す。ガラスブランクの大部分の面はプレス成形型の成形面が転写された面であり、１１０で示した部分が肉厚部成形用空間において、プレス成形型の成形面が転写されずに自由表面となった面である。   The process of press-molding a molten glass lump using a mold having the vertical cross-sectional shape (cross section including the central axis of the mold) shown in FIG. 1 was repeated, and a disk-shaped glass blank was mass-produced experimentally. FIG. 7 shows the vertical cross-sectional shape (cross section including the central axis) of the obtained glass blank. Most of the surface of the glass blank is the surface onto which the molding surface of the press mold has been transferred, and the portion indicated by 110 is the free surface without the molding surface of the press molding die being transferred in the thick part molding space. This is the surface.

図7に示したガラスブランクの各部寸法は設計値と等しくなっている。このようにして作製したガラスブランクの真円度、外径公差、肉厚公差、平行度を測定した。その結果、量産したガラスブランクの全数（１０００枚）の９５％以上が、真円度０．０５ｍｍ以内、外径公差±０．１ｍｍ以内、肉厚公差±０．０１５ｍｍ以内、平行度０．０１ｍｍ以内に収まっていた。   The dimensions of each part of the glass blank shown in FIG. 7 are equal to the design values. The roundness, outer diameter tolerance, wall thickness tolerance, and parallelism of the glass blanks thus produced were measured. As a result, 95% or more of the total number of glass blanks produced (1000 sheets) are roundness within 0.05mm, outer diameter tolerance within ± 0.1mm, wall thickness tolerance within ± 0.015mm, parallelism 0.01mm. Was within.

外縁部の凸部が全周にわたり形成され、その幅は０．５ｍｍ、高さは厳密には一定ではないが０．５ｍｍである。このようにガラスブランクの外縁部に肉厚部を設けることにより断面二次モーメントが増加してガラスブランクの平面度が低下しにくくなる。本実施例では平面度は平均０．０３ｍｍ前後であり、上記肉厚部がない場合と比較して平面度を１０〜２０％程度改善することができた。   A convex part of the outer edge part is formed over the entire circumference, the width is 0.5 mm, and the height is 0.5 mm although it is not strictly constant. Thus, by providing a thick part in the outer edge part of a glass blank, a cross-sectional secondary moment increases and the flatness of a glass blank becomes difficult to fall. In this example, the flatness was about 0.03 mm on average, and the flatness could be improved by about 10 to 20% as compared with the case where there was no thick part.

こうして真円度、外径公差、肉厚公差、平行度、平面度ともに優れたガラスブランクを一連のプレス成形により１０００枚得た。   Thus, 1000 glass blanks having excellent roundness, outer diameter tolerance, wall thickness tolerance, parallelism, and flatness were obtained by a series of press molding.

（比較例１）
実施例1で、成形型の外周構造を変更して、プレス成形時に外周が規制されず、外周面が自由表面になるようにプレス成形を行った。その結果、得られたガラスブランクの真円度は０．０５〜０．１３ｍｍ程度、外径ばらつきは０．２〜０．５ｍｍとなった。 (Comparative Example 1)
In Example 1, the outer peripheral structure of the mold was changed, and press molding was performed so that the outer periphery was not restricted during press molding and the outer peripheral surface was a free surface. As a result, the roundness of the obtained glass blank was about 0.05 to 0.13 mm, and the outer diameter variation was 0.2 to 0.5 mm.

（比較例２）
次に、実施例1のように成形型によって外周を規制するものの、成形面外周端と外周規制面の間に空間を設けず、外縁部に肉厚部が形成されないようにプレス成形を行った。 その結果、得られたガラスブランクの肉厚ばらつきは０．０１５ｍｍ程度、平行度は０．０２〜０．０４ｍｍであった。また、平面度は０．０５ｍｍ程度であり、複数枚積載して徐冷したとき、平面度は０．１ｍｍ前後まで悪化した。 (Comparative Example 2)
Next, although the outer periphery was regulated by a molding die as in Example 1, no space was provided between the outer peripheral edge of the molding surface and the outer circumference regulating surface, and press molding was performed so that a thick portion was not formed at the outer edge portion. . As a result, the thickness variation of the obtained glass blank was about 0.015 mm, and the parallelism was 0.02 to 0.04 mm. Moreover, the flatness was about 0.05 mm, and when a plurality of sheets were stacked and cooled slowly, the flatness deteriorated to around 0.1 mm.

（実施例2）
実施例1で得られたガラスブランクを複数枚、積載して徐冷して歪を低減した。 (Example 2)
A plurality of glass blanks obtained in Example 1 were stacked and gradually cooled to reduce strain.

次に、ガラスブランクの主表面をラッピングにより研削し、両主表面を平坦に加工した。その際、中央凸部および外縁凸部が形成されている主表面に対して反対側の主表面を基準面とした。   Next, the main surface of the glass blank was ground by lapping, and both main surfaces were processed to be flat. At that time, the main surface opposite to the main surface on which the central convex portion and the outer peripheral convex portion are formed was used as a reference plane.

次に、外周面を基準にして円盤状のブランクの中心位置を定め、円形の孔を開ける加工を行った。外周面は型転写面であり、ガラスブランクの真円度も優れているので中心孔開け加工の際、上記のように中心位置決めの基準面としてガラスブランクの外周面を利用することができる。ガラスブランクを主表面方向から平面視したときの外周面の輪郭線を中心孔開け加工の際の孔開け位置を決める基準に使用する手法も上記方法に含まれる。中心孔開け加工後、中心孔の内周面を仕上げ加工してもよい。   Next, the center position of the disc-shaped blank was determined based on the outer peripheral surface, and a process of opening a circular hole was performed. Since the outer peripheral surface is a mold transfer surface and the roundness of the glass blank is excellent, the outer peripheral surface of the glass blank can be used as the reference surface for center positioning as described above when the center hole is drilled. A method of using the outline of the outer peripheral surface when the glass blank is viewed in plan from the main surface direction is used as a reference for determining the drilling position in the center drilling process. You may finish the inner peripheral surface of a center hole after a center hole drilling process.

さらに外周面を加工してもよいが、本実施例のように真円度が高いガラスブランクでは、外周面を加工して得られる基板と外周面を加工していない基板とで回転対称軸の位置は変わらない。したがって、外周面を加工しない基板でも安定した状態で高速回転することができる。外周面加工の手間とコストの低減を優先する場合は、外周面加工を省き、外周面加工フリーの基板、すなわち、外周面がプレス成形型成形面の転写面である基板とすることが望ましい。   Further, the outer peripheral surface may be processed, but in a glass blank having a high roundness as in this embodiment, the rotational symmetry axis of the substrate obtained by processing the outer peripheral surface and the substrate not processed the outer peripheral surface are The position does not change. Therefore, even a substrate whose outer peripheral surface is not processed can be rotated at a high speed in a stable state. When priority is given to reducing the labor and cost of the outer peripheral surface processing, it is desirable to omit the outer peripheral surface processing and use a substrate that is free of outer peripheral surface processing, that is, a substrate whose outer peripheral surface is a transfer surface of a press mold.

さらに、研削した主表面を研磨して平滑な主表面に仕上げ、洗浄して清浄なディスク状の磁気記録媒体用のガラス基板を得る。その他の加工は、公知の加工を適宜適用することができる。   Further, the ground main surface is polished to finish to a smooth main surface and washed to obtain a clean disk-shaped glass substrate for a magnetic recording medium. For other processes, known processes can be applied as appropriate.

Ｌｉ2ＯまたはＮａ2Ｏ、Ｌｉ2ＯおよびＮａ2Ｏを含むガラスで基板を作製する場合、硝酸ナトリウムや硝酸カリウムの熔融塩、あるいは硝酸ナトリウムと硝酸カリウムの混合熔融塩に基板を浸漬し、化学強化してもよい。 When a substrate is made of glass containing Li 2 O or Na 2 O, Li 2 O and Na 2 O, the substrate is immersed in a molten salt of sodium nitrate or potassium nitrate, or a mixed molten salt of sodium nitrate and potassium nitrate, and chemically strengthened. May be.

このようにして得られた各基板は磁気記録媒体用基板、光磁気記録媒体用基板、光ディスクなどの情報記録媒体用基板として好適である。   Each substrate thus obtained is suitable as a substrate for an information recording medium such as a magnetic recording medium substrate, a magneto-optical recording medium substrate, or an optical disk.

（実施例3）
実施例2で得られたガラス基板の表面に磁性層（情報記録層）を含む多層膜を形成して磁気記録媒体（磁気ディスク）を作製した。作製された媒体はいずれも良好に機能することが確認された。 (Example 3)
A multilayer film including a magnetic layer (information recording layer) was formed on the surface of the glass substrate obtained in Example 2 to produce a magnetic recording medium (magnetic disk). It was confirmed that all the produced media functioned well.

なお、情報記録層を含む多層膜の種類を周知の方法により適宜選択することにより光磁気記録媒体や光ディスクなどの他の情報記録媒体を作製することもできる。   Note that other information recording media such as a magneto-optical recording medium and an optical disk can be produced by appropriately selecting the type of multilayer film including the information recording layer by a known method.

このようにして、高い生産性のもとにガラスブランクを作製することができ、その結果、このガラスブランクを用いることにより情報記録媒体用基板や情報記録媒体を生産性よく製造することができる。   Thus, a glass blank can be produced with high productivity. As a result, by using this glass blank, an information recording medium substrate and an information recording medium can be produced with high productivity.

本発明は、情報記録媒体の製造分野に有用である。   The present invention is useful in the field of manufacturing information recording media.

本発明の方法で用いるプレス成形型の一例An example of a press mold used in the method of the present invention 本発明の方法で用いるプレス成形型の一例An example of a press mold used in the method of the present invention 本発明の方法で用いるプレス成形型の一例An example of a press mold used in the method of the present invention 本発明の方法で用いるプレス成形型の一例An example of a press mold used in the method of the present invention 本発明の方法で用いるプレス成形型の一例An example of a press mold used in the method of the present invention 本発明の方法で用いるプレス成形型の一例An example of a press mold used in the method of the present invention 本発明の方法で得られるガラスブランクGlass blank obtained by the method of the present invention

Claims (13)

軟化状態のガラス塊を一対の押圧型でプレス成形する工程を繰り返し行ってガラスブランクを量産する、略円盤状の情報記録媒体用基板ガラスブランクの製造方法において、
繰り返し行われる前記プレス成形は、一対の押圧型の成形面の距離が一定の値になるまで所定量のガラス塊をプレスすること、
軟化状態のガラス塊をプレスして一対の押圧型の対向する２つの成形面に沿ってガラスを伸ばし、伸ばしたガラスの全外周に外周規制面を転写して、ガラスブランクの一対の主表面と外周面を成形するとともに、
成形面の外周部または前記外周部の外側にあって対向する成形面の距離より大きい間隔を有する2つの面および外周規制面によって少なくとも区画される、前記押圧型のキャビティ内の外周に設けられた、肉厚部成形用空間の一部に前記伸ばしたガラスを侵入させて、ガラスブランクの外縁の少なくとも一部に肉厚部を成形する(但し、上記ガラスブランクの外縁の肉厚とならない部分は、前記ガラスブランクの一対の主表面の厚みと少なくとも等しい厚みを有する)こと、
プレス成形毎に供給するガラス塊の量の変動に応じて、肉厚部成形用空間へのガラスの充填度を変化させること、但し、プレス成形毎に供給するガラス塊の量の変動幅および肉厚部成形用空間の容量は、ガラスブランクの外縁の少なくとも一部に肉厚部が形成されるが、肉厚部成形用空間の容量を超えてガラスが充填されない範囲で設定される、
ことを特徴とする情報記録媒体用基板ガラスブランクの製造方法。 In the manufacturing method of a substantially disc-shaped substrate glass blank for an information recording medium in which a glass blank is mass-produced by repeatedly performing a step of press-molding a softened glass lump with a pair of pressing dies,
The press molding performed repeatedly is to press a predetermined amount of glass lump until the distance between the molding surfaces of the pair of pressing dies becomes a constant value,
Press the softened glass lump to stretch the glass along two opposing molding surfaces of the pair of pressing dies, transfer the outer peripheral regulating surface to the entire outer periphery of the stretched glass, While molding the outer peripheral surface,
Provided on the outer periphery in the cavity of the pressing mold, which is at least defined by the outer peripheral part of the molding surface or the outer surface of the outer peripheral part and at least partitioned by two surfaces having a larger distance than the opposing molding surface and the outer peripheral regulating surface , By allowing the stretched glass to penetrate into a part of the thick part forming space, and forming a thick part on at least a part of the outer edge of the glass blank (however, the part that does not become the thickness of the outer edge of the glass blank is , Having a thickness at least equal to the thickness of a pair of main surfaces of the glass blank),
The filling degree of the glass into the thick part forming space is changed according to the fluctuation of the amount of glass lump supplied for each press forming, provided that the fluctuation range and the thickness of the amount of glass lump supplied for each press forming are changed. The capacity of the thick part forming space is set in a range where the thick part is formed on at least a part of the outer edge of the glass blank, but the glass is not filled beyond the capacity of the thick part forming space,
The manufacturing method of the substrate glass blank for information recording media characterized by the above-mentioned. 肉厚部を全周にわたり成形することを特徴する請求項１に記載の情報記録媒体用基板ガラスブランクの製造方法。   The method for producing a substrate glass blank for an information recording medium according to claim 1, wherein the thick part is formed over the entire circumference. プレスの際の、一対の押圧型の成形面の距離の前記一定の値は、０．７〜３．０ｍｍの範囲に設定する請求項１または２に記載の情報記録媒体用基板ガラスブランクの製造方法。 The manufacturing of the substrate glass blank for an information recording medium according to claim 1 or 2, wherein the constant value of the distance between the molding surfaces of the pair of pressing dies is set in a range of 0.7 to 3.0 mm. Method. ガラスブランクは、
（１）一方の主表面の外縁を平坦とし、他方の主表面の外縁を凸部として肉厚部とするか、
（２）両方の主表面の外縁を凸部として肉厚部とすることを特徴とする請求項１〜３のいずれかに記載の情報記録媒体用基板ガラスブランクの製造方法。 Glass blank
(1) The outer edge of one main surface is flattened and the outer edge of the other main surface is a convex part, or a thick part,
(2) The method for producing a substrate glass blank for an information recording medium according to any one of claims 1 to 3, wherein the outer edges of both main surfaces are convex portions to form a thick portion. ガラスブランクは、一方または両方の主表面の中央部に凸部を設けたものである請求項１〜４のいずれかに記載の情報記録媒体用基板ガラスブランクの製造方法。   The method for producing a substrate glass blank for an information recording medium according to any one of claims 1 to 4, wherein the glass blank is provided with a convex portion at a central portion of one or both main surfaces. 押圧型は、型閉めした状態で上型と下型とが直接当接する構造を有する請求項１〜５のいずれかに記載の情報記録媒体用基板ガラスブランクの製造方法。   The method for manufacturing a substrate glass blank for an information recording medium according to any one of claims 1 to 5, wherein the pressing die has a structure in which the upper die and the lower die are in direct contact with each other in a closed state. 前記押圧型の一方が前記外周規制面を備え、One of the pressing molds includes the outer peripheral restriction surface,
前記供給されたガラスは、前記肉厚部の凸部を形成する表面の一部または全部が型に接触せずに自由表面となっていることを特徴とする請求項６に記載の情報記録媒体用基板ガラスブランクの製造方法。7. The information recording medium according to claim 6, wherein a part or all of a surface of the supplied glass forming the convex portion of the thick portion is a free surface without being in contact with a mold. For manufacturing substrate glass blanks. 軟化状態のガラス塊が熔融ガラス塊であり、この熔融ガラス塊を一方の押圧型の成形面中央に供給してプレス成形する請求項１〜７のいずれかに記載の情報記録媒体用基板ガラスブランクの製造方法。 The substrate glass blank for an information recording medium according to any one of claims 1 to 7 , wherein the softened glass lump is a molten glass lump, and the molten glass lump is supplied to the center of the molding surface of one pressing mold and press-molded. Manufacturing method. 肉厚部成形用空間の容量は、
プレス成形毎に供給するガラス塊の量の変動により生じると想定される最大量のガラスが、肉厚部成形用空間以外の押圧型のキャビティ内に隙間が生じないように均一に供給されたと想定した場合に、肉厚部成形用空間においてガラスが占める断面積の１１０％〜２００％の断面積を持つように設定されることを特徴とする請求項１〜８のいずれかに記載の情報記録媒体用基板ガラスブランクの製造方法。 The capacity of the thick part molding space is
It is assumed that the maximum amount of glass that is assumed to be generated due to fluctuations in the amount of glass lump that is supplied for each press molding is supplied uniformly so that there is no gap in the cavity of the pressing mold other than the thick part forming space. The information recording according to any one of claims 1 to 8 , wherein the information recording is set so as to have a cross-sectional area of 110% to 200% of a cross-sectional area occupied by the glass in the thick part forming space. A method for producing a substrate glass blank for a medium. 請求項１〜９のいずれかに記載の方法でガラスブランクを製造し、製造したガラスブランクの外周面を基準に中心孔開け位置を定め、中心孔開け加工する工程、中心孔開け加工したブランクの２つの主表面を研削する工程、研削した主表面を研磨する工程を有する情報記録媒体用基板の製造方法。 A glass blank is manufactured by the method according to any one of claims 1 to 9 , a step of determining a center hole position on the basis of an outer peripheral surface of the manufactured glass blank, a step of processing a center hole, A method for manufacturing a substrate for an information recording medium, comprising a step of grinding two main surfaces and a step of polishing the ground main surface. プレス成形で成形した平坦な主表面を基準にして、主表面の研削を行う請求項１０に記載の情報記録媒体用基板の製造方法。 The method for manufacturing a substrate for an information recording medium according to claim 10 , wherein the main surface is ground with reference to a flat main surface formed by press molding. プレス成形で成形した外縁の肉厚部を基準にして、主表面の研削を行う請求項１０に記載の情報記録媒体用基板の製造方法。 The method for manufacturing a substrate for an information recording medium according to claim 10 , wherein the main surface is ground on the basis of the thick part of the outer edge formed by press molding. 請求項１０〜１２のいずれかに記載の方法で基板を作製し、作製した基板上に情報記録層を含む膜を形成する工程を有する情報記録媒体の製造方法。 A method for producing an information recording medium, comprising : producing a substrate by the method according to any one of claims 10 to 12 ; and forming a film including an information recording layer on the produced substrate.
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